This invention relates to the field of compatible AM stereo signals and, more particularly, to the provision of an improved means of restoring stereo program signals.
In one known receiver for decoding stereo signals from a received signal of the form (1+L+R)cos (.omega..sub.c t+.phi.) where .phi. is arc tan[(L-R)/1+L+R)], approximate stereo signals of the form R cos .phi. and L cos .phi. were obtained from two synchronous detectors. This receiver was disclosed in U.S. Ser. No. 7,733 filed Jan. 30, 1979. A cos .phi. correction signal was determined by means of a limiter and phase locked loop, and the two approximate signals were divided by the cos .phi. correction signal to retrieve the stereo information signals. Another receiver disclosed in Ser. No. 837,258, filed Sept. 27, 1977, derived the sum signal (1+L+R) by means of an envelope detector, and the difference signal was obtained from a signal (L-R)cos .phi. by division by a signal proportional to cos .phi..